Kernel: Create RecursiveSpinLock and add it to Process

We now lock every function within Proccess, just to be sure.
Recursive lock allows us to use lock from the same thread even if
we already have the spinlock locked

kernel/kernel/SpinLock.cpp

@@ -1,4 +1,5 @@
 #include <kernel/SpinLock.h>
+#include <kernel/Thread.h>
 
 namespace Kernel
 {
@@ -21,4 +22,35 @@ namespace Kernel
 		return m_lock;
 	}
 
+	void RecursiveSpinLock::lock()
+	{
+		// FIXME: is this thread safe?
+		if (m_locker == Thread::current()->tid())
+		{
+			m_lock_depth++;
+		}
+		else
+		{
+			m_lock.lock();
+			ASSERT(m_locker == 0);
+			m_locker = Thread::current()->tid();
+			m_lock_depth = 1;
+		}
+	}
+
+	void RecursiveSpinLock::unlock()
+	{
+		m_lock_depth--;
+		if (m_lock_depth == 0)
+		{
+			m_locker = 0;
+			m_lock.unlock();
+		}
+	}
+
+	bool RecursiveSpinLock::is_locked() const
+	{
+		return m_lock.is_locked();
+	}
+
 }